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- /*-----------------------------------------------------------------------------
- * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
- *
- * $Date: 17. January 2013
- * $Revision: V1.4.1
- *
- * Project: CMSIS DSP Library
- * Title: arm_biquad_cascade_df1_init_f32.c
- *
- * Description: floating-point Biquad cascade DirectFormI(DF1) filter initialization function.
- *
- * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * - Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * - Neither the name of ARM LIMITED nor the names of its contributors
- * may be used to endorse or promote products derived from this
- * software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- * ---------------------------------------------------------------------------*/
-
- #include "arm_math.h"
-
- /**
- * @ingroup groupFilters
- */
-
- /**
- * @addtogroup BiquadCascadeDF1
- * @{
- */
-
- /**
- * @details
- * @brief Initialization function for the floating-point Biquad cascade filter.
- * @param[in,out] *S points to an instance of the floating-point Biquad cascade structure.
- * @param[in] numStages number of 2nd order stages in the filter.
- * @param[in] *pCoeffs points to the filter coefficients array.
- * @param[in] *pState points to the state array.
- * @return none
- *
- *
- * <b>Coefficient and State Ordering:</b>
- *
- * \par
- * The coefficients are stored in the array <code>pCoeffs</code> in the following order:
- * <pre>
- * {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...}
- * </pre>
- *
- * \par
- * where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage,
- * <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage,
- * and so on. The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values.
- *
- * \par
- * The <code>pState</code> is a pointer to state array.
- * Each Biquad stage has 4 state variables <code>x[n-1], x[n-2], y[n-1],</code> and <code>y[n-2]</code>.
- * The state variables are arranged in the <code>pState</code> array as:
- * <pre>
- * {x[n-1], x[n-2], y[n-1], y[n-2]}
- * </pre>
- * The 4 state variables for stage 1 are first, then the 4 state variables for stage 2, and so on.
- * The state array has a total length of <code>4*numStages</code> values.
- * The state variables are updated after each block of data is processed; the coefficients are untouched.
- *
- */
-
- void arm_biquad_cascade_df1_init_f32(
- arm_biquad_casd_df1_inst_f32 * S,
- uint8_t numStages,
- float32_t * pCoeffs,
- float32_t * pState)
- {
- /* Assign filter stages */
- S->numStages = numStages;
-
- /* Assign coefficient pointer */
- S->pCoeffs = pCoeffs;
-
- /* Clear state buffer and size is always 4 * numStages */
- memset(pState, 0, (4u * (uint32_t) numStages) * sizeof(float32_t));
-
- /* Assign state pointer */
- S->pState = pState;
- }
-
- /**
- * @} end of BiquadCascadeDF1 group
- */
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